Getting input one character at a time doesn't involve using select and non-blocking I/O (at least not the easiest way). The way that the input is processed is set by the user's terminal. The default setting is known as 'canonical mode', which processes line-by-line. I also must correct my original statement, for there is indeed a way with the standard perl modules to do what you want. For example:

use POSIX qw(:termios_h);

my $termios = new POSIX::Termios;

$termios->setlflag(~ICANON);     # Turn off canonical mode
$termios->setcc(VMIN, 1);        # Read a min of 1 character
$termios->setcc(VTIME, 0);       # No time-out on reads
$termios->setattr(0, TCSANOW);   # Apply settings to STDIN

while(read(STDIN, $key, 1)) {
        print "Got: $key\r\n";
}
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or something similar will work. The flags and function calls used by the POSIX::Termios module are nearly identical to the corresponding ones in C.